WASHINGTON, May 3 (Reuters) - In a possible breakthrough for
U.S. Republicans' chaotic effort to roll back Obamacare, three
moderate lawmakers emerged from a White House meeting with
President Donald Trump on Wednesday and said a revised bill
might pass. But pitfalls still lay ahead.

Keen to score his first major legislative win since taking
office in January, Trump has been personally engaged this week
in trying to cement support among fellow Republicans in the
House of Representatives for an effort that has twice before
collapsed in confusion.

The bill has been changed several times as Republican
leaders try to balance demands by conservatives seeking a
maximum rollback of the Affordable Care Act with the concerns of
moderates worried about angering voters who value parts of it.

The moderates, speaking to reporters outside the White
House, said Trump has endorsed their plan to add $8 billion over
five years to help cover the cost for people with pre-existing
illnesses who could otherwise be priced out of insurance
markets.

Representative Fred Upton said it now seemed likely the bill
would pass the House, although a moderate colleague,
Representative Billy Long, said Republicans still seemed short
of the votes needed.

"There's still work to be done on the votes," he said.

Aides said Trump has been working the phones furiously in an
effort to drum up support and score a victory on one of his key
priorities, which is to overhaul Democratic former President
Barack Obama's signature domestic legislation. The effort to
push through a healthcare bill is showing Trump the challenge of
placating various Republican factions.

An initial attempt foundered in the House and was withdrawn
by Republican leaders in March, a defeat that cast a shadow over
Trump's first 100 days in office. Republicans renewed
negotiations last month at the White House’s urging, but failed
to round up enough support for a vote before a two-week recess
in April. Republicans are now hoping to get something passed
before they leave for another recess on Thursday evening.

Health insurers such as Anthem Inc, UnitedHealth
Group, Aetna Inc and Cigna Corp have faced
months of uncertainty over the future of the country's
healthcare system.

Millions more Americans got healthcare coverage under
Obamacare, which was passed in 2010, but Republicans have long
sought to overturn it, seeing it as government overreach and
complaining it drives up costs.

House Democrats rejected the latest proposed change to the
Republican legislation on Wednesday, saying it appears to
protect patients with pre-existing conditions, but some could
still be pushed off their insurance in certain states and face
higher costs.

U.S. House Speaker Paul Ryan said Upton's proposed changes
were uncontroversial and were unlikely to alienate more
hard-line conservatives, who had blocked an earlier rollback
effort.

"There is not a problem," Ryan said in an interview on the
Hugh Hewitt radio show, adding that Mark Meadows, chairman of
the conservative House Freedom Caucus, was aware of the effort.

Asked when the House would vote on a final version of a
bill, Ryan said: "We're getting extremely close."

Long said he had opposed the legislation until the
pre-existing conditions were covered and he had resisted Trump's
arm-twisting. Long said he now supported it.

"The president said, 'Billy we really need you, man,'" he
added.

Even if the bill passes the House, it faces an uphill battle
in the Senate. The nonpartisan Congressional Budget Office
estimated an earlier version of the bill would leave 24 million
more people without insurance in 2026.

Called the American Health Care Act, the Republican bill
repeals most Obamacare taxes, including a penalty for not buying
health insurance. It slashes funding for Medicaid, the program
to provide insurance for the poor, and rolls back much of its
expansion, while swapping Obamacare’s income-based tax credits
for flat age-based credits.

An amendment recently added to win over the Freedom Caucus
lets states opt out of Obamacare’s mandate that insurers charge
sick and healthy people the same rates. But Wednesday's
amendment from Upton aimed to assauge moderates' concerns about
that by providing a way for people with pre-existing conditions
to get financial help to afford insurance. Others said the $8
billion over five years was not enough.

Drawing more public attention to the debate in Washington,
late night talk show host Jimmy Kimmel tearfully revealed on
Monday evening that his newborn son had a congenital heart
condition, saying it brought home to him the importance of
health coverage for people with such pre-existing illnesses.

As of Wednesday morning, Kimmel's monologue had been viewed
nearly 17 million times on his show's Facebook page and was the
No. 1 trending story on YouTube, viewed more than 9.2 million
times. It was shared nearly 258,000 times on his personal page.
(Reporting by David Morgan, Richard Cowan, Susan Heavey, Doina
Chiacu, Jeff Mason and Yasmeen Abutaleb; Writing by Steve
Holland and Doina Chiacu; Editing by Kevin Drawbaugh and Frances
Kerry)